Airo 15: 11-17 (2005)
CONSERVATION OF PUFFINUS SPECIES I N T H E
AZORES
MARIA PITTA GROZ1 , L.R. MONTEIRO*, J.C. PEREIRA2, A.G. SILVA3 & J.A. RAMOS4
SUMMARY - Historical data on the Azores breeding Puffinus species is reviewed through the
analysis of historical chronicles from the 16th and 17th century. The seabird populations of the
Azores suffered dramatic declines following the colonisation of the islands mainly due to habitat
destruction, the introduction of predators and direct human exploitation. Inventories of all the seabirds
populations became available only recently and the first comprehensive surveys of shearwaters and
petrels of the Azores were conducted from 1996 to 1998. The surveys detected 12 new locations of
Puffinus puffinus on Flores and Corvo islands, with a total estimated population of 115-235 pairs.
A total of 68 new locations of Puffinus assimilis were detected on all islands, except Terceira, with
a total estimate of 840-1530 pairs. A revision of the Azores Special Protection Areas Network was
proposed on the basis of that information, enlarging the present area by approximately 80%.
Management plans for seven Special Protection Areas were produced. The present status of Manx
Shearwater Puffinus puffinus and Little Shearwater Puffinus assimilis populations is outlined
and conservation-orientated research priorities are discussed.
CONSERVAÇÃO DAS ESPÉCIES DO GÉNERO PUFFINUS NOS AÇORES –
Dados históricos das espécies de Procellariiformes nidificantes nos Açores foram revistos através da
análise de crónicas históricas dos séculos XVI e XVII. As populações de aves marinhas dos Açores
sofreram declínios dramáticos no seguimento da colonização das ilhas essencialmente devido à destruição
do habitat, à introdução de predadores e à exploração directa pelo homem. Inventários de todas as
populações de aves marinhas tornaram-se disponíveis apenas recentemente e o primeiro censo exaustivo
das espécies de pardelas e painhos que nidificam no arquipélago dos Açores decorreu entre 1996 e
1998. Os censos registaram 12 novas colónias de Pintainho Puffinus assimilis nas ilhas das Flores
e Corvo, com uma população total estimada em 115-235 casais. Paralelamente foram registadas 68
novas colónias de Fura-bucho do Atlântico Puffinus puffinus em todas as ilhas, com excepção da
Terceira, com uma população total estimada em 840-1530 casais. Com base nessa informação foi
proposta uma revisão da rede de Zonas de Protecção Especial dos Açores, que aumenta em cerca de
80% a área designada. Foram produzidos planos de gestão para sete Zonas de Protecção Especial. O
actual estatuto de conservação do Fura-bucho do Atlântico Puffinus assimilis e do Pintainho
Puffinus puffinus é apresentado e prioridades de investigação aplicadas à conservação são discutidas.
The Azores archipelago consists of nine volcanic
islands and numerous small islets, forming three
groups along a tectonic zone running WNW-ESE
between 37º and 40ºN latitude, 25º and 32ºW
longitude, in the middle of the Atlantic Ocean ca.
1500 km west of mainland Portugal. The islands are
the emergent part of underwater volcanoes with very
narrow insular platforms that descend rapidly to
depths of 2000-3000 m in the channels between
islands. Submerged seamounts (banks) are important
topographic features and their combined area at 500m
depth exceeds 2,160 km2 (Tucker & Evans 1997).
Surrounded by the Atlantic Ocean, the Azores
have a mild climate: low thermal amplitude, high
1
Direcção Regional do Ambiente Colónia Alemã 9900-014 Horta, Portugal. e-mail: [email protected] / 2SilpermarAquaculture, Avenida Humberto Delgado nº6A 2860-021 Alhos Vedros, Portugal / 3Instituto Superior de Psicologia
Aplicada, Rua Jardim do Tabaco, 1149-041 Lisboa, Portugal / 4IMAR, Depto Zoologia, Fac. Ciência e Tecnologia,
Universidade de Coimbra, 3004-517 Coimbra, Portugal / * tragically killed in a plane accident on the 11th December 1999
12
CONSERVATION OF PUFFINUS SPECIES IN THE AZORES
precipitation and humidity are properties of this
archipelago with a marked oceanic climate (Borges
1990). These warm-water seas are characterised by
low relatively stable levels of productivity (Raymont
1980) but that can be substantially elevated locally,
due to upwellings at seamounts, island shelfbreaks
and thermal fronts.
On land, the natural vegetation of the Azores
islands is composed of a fairly large number of
endemic plant communities, originated to some
extent from the Tertiary Period. These plant
communities are susceptible to environmental
change and invasion of alien species, in many cases
being a consequence of such changes. Plant
communities differ in all the islands depending on
factors that include altitude, climate, topography,
geological differentiation and human influence
(Sjogren 1973).
The Azores were uninhabited by humans until
1433 when they were colonised by the Portuguese.
The discovery of the Azores islands took place in
1427 in Santa Maria island and proceeded
westwards until 1452, with the discovery of Flores
and Corvo. Human settlement and land use had
different levels of impact in the islands of the
archipelago but the intensive use of the coast and
its resources has been a common factor affecting
seabird colony distribution since then. The
introduction, accidental or intentional, of invasive
alien plants and mammals together with the
intensive exploitation of natural resources as a
result of colonisation, caused significant changes
in the natural habitats and communities of the
Azores archipelago. In this paper historical data of
the Azores breeding Procellariiformes is reviewed
focusing on the available information of Manx
Shearwater Puffinus puffinus and Little Shearwater
Puffinus assimilis. The present status, distribution,
conservation and management of these two
species are outlined in order to provide a
discussion on the conservation-orientated research
priorities.
HISTORICAL REVIEW
The historical chronicles of Gaspar Frutuoso
dating from 1561 list eight Procellariiformes among
10 seabird species distributed through all the islands
of the archipelago in abundant colonies. The
breeding seabirds of the Azores archipelago
currently comprise five species of Procellariiformes
that include Bulwers’ Petrel Bulweria bulwerii, Cory’s
Shearwater Calonectris diomedea, Manx Shearwater
Puffinus puffinus, Little shearwater Puffinus assimilis
and Madeiran Storm Petrel Oceanodroma castro
(Monteiro et al. 1999). Two other species of
Procellariiforme referred as “calca-mar” and
“boeiro” are mentioned by Monteiro et al. (1996) as
being the possible former breeders White-faced
Storm Petrel Pelagadroma marina and Fea’s Petrel
Pterodroma feae, respectively. The species named
“Alauda” referred as occurring in Ilhéu de Baixo
(Graciosa) and solely used for the production of oil
remains unidentified.
According to Warham (1996) seabirds, including
petrels, were a mainstay of the economy of some
human populations. In the Azores, according to
Frutuoso (1561-printed as Frutuoso 1983) two
main species were intensively captured, “Pardela”
and “Estapagado” considered to be Bulwer’s petrel
and Manx shearwater respectively by Monteiro et al.
(1996). The Procellariiformes were harvested in
different periods of the year according to the
breeding period of the species and the use of the
resources. The adults would be captured for food
and cooked fresh or salted like fish for later
consumption. There are also references to the use
of these birds to feed pigs. The feathers collected
were used in beds and covers. The young birds
would be captured later in the season for their
stomach oil. Ten birds would produce
approximately 2 l of oil (Frutuoso 1561-printed as
Frutuoso 1983). The Manx Shearwaters were
captured from January to April using fire to attract
the birds and dogs to capture them. The
exportation of “estapagados” from the island of
Corvo to Flores and the market price of “1/2
vintém” for 8 to 10 “pardelas” reveals the economic
importance of this species at that time (Frutuoso
1561 - printed as Frutuoso 1983). It is clear that
enormous amounts of “estapagados” were
captured following human colonisation as indicated
by the mention of captures of 10,000 individuals
per night and the references to people specialised in
hunting seabirds (Frutuoso 1561 - printed as
Frutuoso 1983).
According to the historical chronicles of Gaspar
Frutuoso Manx shearwaters were abundantly
M. PITTA-GROZ, L.R. MONTEIRO, J.C. PEREIRA, A.G. SILVA & J.A. RAMOS
present in São Miguel, Santa Maria, Terceira,
Graciosa, São Jorge, Flores and Corvo at the time
of colonisation. Later, in the 16th century, a
significant decline in the abundance of
“estapagados” and “pardelas” is mentioned and
related to predation by ferrets Mustela furo. In the
early days of settlement, there is also indication of
conflicts between the use of land for agricultural
purposes and the burrowing behaviour of
procellariiform species. This conflict must have
intensified the exploitation of these bird species as
an economic resource, limiting in a dramatic way,
until the present days, the distribution of these
species in the archipelago.
STATUS AND DISTRIBUTION
Puffinus puffinus
The Manx shearwater has a large world
population (ca. 300,000 pairs) concentrated at a few
sites off North-west Europe and it is a SPEC
(Category 2) species with a threat status of localised
(Tucker & Heath 1994). In the Macaronesian
islands the species has small colonies and in recent
years there is evidence of falling numbers (Tucker
& Heath 1994).
The first comprehensive surveys of small to
medium-sized shearwaters and petrels in the Azores
archipelago, conducted from 1996 to 1998 detected
12 new locations of Puffinus puffinus on Flores and
Corvo islands at the edges of inaccessible high
cliffs where closer inspection was impossible
(Monteiro et al. 1999). Four discrete breeding
colonies were delimited according to presence or
absence of birds calling associated with physical
discontinuities (Monteiro et al. 1999). A total
population of 115-235 pairs was estimated
(Monteiro et al. 1999). Sea watches recorded rafts of
ca. 50 individuals off Pão de Açúcar-Pingas
(Corvo), both in mid April and early July (Monteiro
et al. 1999). Other records for this species are listed
in Table 1.
Puffinus assimilis
The endemic European race of the Little
Shearwater, Puffinus assimilis baroli, breeds in the
archipelagos of Madeira, Canaries and the Azores
with an estimated population of 2,700-3,900 pairs
(Tucker & Heath 1994).
13
The first comprehensive surveys of small to
medium-sized shearwaters and petrels in the Azores
archipelago, conducted from 1996 to 1998 detected
68 new locations of Puffinus assimilis on all islands,
except Terceira (Monteiro et al. 1999). Virtually all
locations occurred along inaccessible high cliffs and
closer inspection was impossible. Most of the cliffs
where calls of P. assimilis were heard seemed to have
layers of soil for cavities, with little cover of Cane
grass Arundo donax. In several cliffs in Santa Maria
and S. Miguel islands it was clear that apparently
occupied cliffs had very little A. donax, whereas
nearby unoccupied cliffs were covered with this
exotic plant species. Discrete breeding colonies
were delimited according to presence/absence of
birds calling associated with physical discontinuities
(Monteiro et al. 1999). It was possible to confirm
breeding on Morro de Castelo Branco (Faial) where
an active nest site with a broken egg was found in
the 4th May 1998 (Monteiro et al. 1999). With the
addition of new sites a total population of 8401530 pairs was estimated (Monteiro et al. 1999).
MAIN THREATS
According to the historical chronicles (Frutuoso
1561-printed as Frutuoso 1983) past threats include
intensive human exploitation and habitat
deterioration. Although human exploitation no
longer constitutes a threat to these species habitat
deterioration is a present threat and encompasses
several aspects such as introduced predators,
increased native predators, coastal development and
vegetation change at nest sites (Tucker & Evans
1997). The introduction of alien mammals from
continents, particularly predators, such as cats Felis
catus and rats Rattus sp., has been a major factor
contributing to the extinction of bird species in
islands (Moors et al. 1992). In the Azores the past
and present occurrence of predators such as Mus
musculus, Rattus rattus, Rattus norvegicus, Felis catus,
Mustela nivalis and Mustela furo has had a profound
impact in the populations of small Procellariiformes depriving ground nesting birds of using
otherwise suitable breeding sites (Tucker & Evans
1997). Colonies are now largely confined to
precipitous cliffs and islets and it is likely that birds
have either moved to such sites from more
accessible areas, or that only those colonies in
14
CONSERVATION OF PUFFINUS SPECIES IN THE AZORES
Table 1. Records of Manx Shearwater Puffinus puffinus in the Azores archipelago. / Tabela 1. Registos de Fura-bucho do
Atlântico Puffinus puffinus no arquipélago dos Açores.
Place and date
Occurrence
Author
Flores, May 1865
2 adults taken from holes with eggs in the
ovaries*
Godman 1866
Santa Maria, 1903
specimen record
Colecção do Museu Carlos Machado
Corvo, 16 June 1929
1 egg in poor condition
Chavigny & Mayaud 1932
Corvo, July 1931
specimen record
Chavigny & Mayaud 1932
Flores, April 1962
12 birds of the south coast
Bannerman & Bannerman 1966
São Miguel, 7 September 1983 1 abandoned egg*
Le Grand 1993
Flores, June 1994
1 bird calling in Fajã Grande
Monteiro et al. 1999
Corvo, July 1994
few birds at sea
Monteiro et al. 1999
Santa Maria, 1994
individual without brood patch
Monteiro et al. 1999
Santa Maria, 27 March 1998
1 bird caught on the ground of Vila islet
without a brood patch
Monteiro et al. 1999
Santa Maria, 9 August 1998
1 bird caught on the ground of Vila islet
Monteiro et al. 1999
Santa Maria, 1996-1998
1 bird calling off Vila islet
Monteiro et al. 1999
Graciosa, 1996-1998
1 bird calling off Praia islet
Monteiro et al. 1999
Santa Maria, 2000
2 birds on the ground of Vila islet
Pereira pers. com.
Flores, May 2000
numerous birds calling in Fajã Lopo Vaz
Pereira pers. com.
inaccessible sites have survived (Monteiro et al.
1999). Therefore breeding biotopes may be the
limiting factor for the present populations of
Procellariiformes (Ramos et al. 1997). Changes in
the coastal plant communities mainly due to the
invasion of A. donax (Sjogren 1973) has resulted in
major losses of suitable burrowing ground
(Monteiro et al. 1995) and high levels of
intraspecific and interspecific interference
competition for nest cavities may be a result of
alteration of breeding habitat in historical times
(Ramos et al. 1997). The reduction in exploitation of
Cory’s shearwater by humans may lead to greater
pressure for nest cavities but this fact can be
mitigated by building artificial nests for small
petrels that are impossible to be excavated by Cory’s
shearwater (Ramos et al. 1997, Bolton et al. 2004).
Coastal developments such as hotels, marinas and
other tourist facilities, housing or industrial and
agricultural land-claim can threaten seabirds by
destruction of nesting sites and has a widespread
impact in the Macaronesian archipelagos (Tucker &
Evans 1995). Fortunately, oil pollution, to which
Puffinus puffinus is considered highly vulnerable
(Tucker & Evans 1995), is less frequent in the
Macaronesian seas.
CONSERVATION AND MANAGEMENT
Islands seabird populations are highly
vulnerable and predisposed to extinction (Diamond
1985). The first inventory of the Important Bird
Areas in Europe listed 7 sites recognising that the
populations of seabirds breeding in the Azores
were poorly known at the time (Grimmet & Jones
1989). But the first legal action towards the
conservation of wild birds was the adoption of the
Birds Directive in 1990 in the Autonomous Region
of the Azores designating a total of 15 Special
Protection Areas.
Recent inventories of the Azores breeding
seabirds identified important breeding sites and
provided population estimates (Monteiro & del
Nevo 1992, Monteiro et al. 1996, Monteiro et al.
M. PITTA-GROZ, L.R. MONTEIRO, J.C. PEREIRA, A.G. SILVA & J.A. RAMOS
15
Figure 1. Map of the Azores archipelago showing the actual SPA area (black) and the enlargement area
(grey) recently proposed by Monteiro & Groz (1999) plotted against the breeding colonies of Puffinus
puffinus (black arrows) and the breeding colonies of Puffinus assimilis (white arrows) reported by Monteiro, et
al. (1999): 1-Ponta do Marco to Pico João de Moura, 2-Pão de Açúcar to Pingas, 3-Ponta do Marco-Coroa
do Pico, 4-Pão de Açúcar, 5-Alagoa, 6-Fajã da Gata to Peniche, 7-Ponta da Fajã-Fajã Grande, 8-Ponta dos
Ilhéus-Fajã Lopo Vaz, 9-Ponta da Caveira-Ponta Fernão Jorge, 10-Baixa do Moínho-Alagoa, 11-Ilhéu
Furado-Cabouco, 12-Morro Castelo Branco, 13-Ribeira Funda, 14-Mistério da Praínha-Baía de Canas, 15Terra Alta, 16-Foros, 17-Mingato, 18-Ponta Ruiva-Fajã João Dias, 19-Pico do Loiçano, 20-Fajã Santo Cristo,
21-Fajã Cubres-Fajã do Labaçal, 22-Ilhéu de Baixo, 23-Ilhéu da Praia, 24-Ponta da Barca, 25-Ponta da
Ferraria-Ponta do Escalvado, 26-Porto Santa Iria, 27-Fajã Araújo-Água Retorta, 28-Ilhéu da Vila, 29-Baía do
Raposo-Baía do Salto dos Cães, 30-Ponta do Norte, 31-Pontinha-Ponta do Cedro, 32-Ponta do CasteloMalbusca. / Figura 1. Mapa do Arquipélago dos Açores onde se encontra representada a actual rede de ZPE (preto) e a
proposta de alargamento (cinzento) recentemente proposta por Monteiro & Groz (1999) e as colónias de Puffinus puffinus
(setas pretas) e Puffinus assimilis (setas brancas) de acordo com Monteiro et al. (1999): 1-Ponta do Marco to Pico João de
Moura, 2-Pão de Açúcar to Pingas, 3-Ponta do Marco-Coroa do Pico, 4-Pão de Açúcar, 5-Alagoa, 6-Fajã da Gata to
Peniche, 7-Ponta da Fajã-Fajã Grande, 8-Ponta dos Ilhéus-Fajã Lopo Vaz, 9-Ponta da Caveira-Ponta Fernão Jorge, 10Baixa do Moínho-Alagoa, 11-Ilhéu Furado-Cabouco, 12-Morro Castelo Branco, 13-Ribeira Funda, 14-Mistério da
Praínha-Baía de Canas, 15-Terra Alta, 16-Foros, 17-Mingato, 18-Ponta Ruiva-Fajã João Dias, 19-Pico do Loiçano, 20Fajã Santo Cristo, 21-Fajã Cubres-Fajã do Labaçal, 22-Ilhéu de Baixo, 23-Ilhéu da Praia, 24-Ponta da Barca, 25-Ponta
da Ferraria-Ponta do Escalvado, 26-Porto Santa Iria, 27-Fajã Araújo-Água Retorta, 28-Ilhéu da Vila, 29-Baía do
Raposo-Baía do Salto dos Cães, 30-Ponta do Norte, 31-Pontinha-Ponta do Cedro, 32-Ponta do Castelo-Malbusca.
16
CONSERVATION OF PUFFINUS SPECIES IN THE AZORES
1999, Furness et al. 2000). This work allowed the
identification of 15 Important Bird Areas in
Europe recently promoted by Birdlife International
and made clear that the actual SPA of the region
covered only 21% of that area. A revision of the
Azores Special Protection Areas Network was
proposed on the basis of that information
enlarging the present area approximately 80%
(22,028 ha that represent 9.4% of the region’s
territory, see Figure 1) (Monteiro & Groz 1999).
Conservation and management programmes for
seabirds are quite recent in the region. Only in 1998,
a Governmental Nature Conservation Department
was created aiming at the implementation of
management plans for protected areas and species.
However management actions such as the
eradication of introduced mammals from SPAs
(Ilhéu de Vila Franca do Campo in São Miguel and
Ilhéu da Praia in Graciosa), habitat rehabilitation
actions (Ilhéu de Vila Franca do Campo on São
Miguel, Ilhéu do Topo on São Jorge and Ilhéu da
Praia on Graciosa) the allocation of wardens to
more accessible SPAs (Flores, Terceira, Graciosa
and Faial), the allocation of interpretation signs to
all the region SPAs and the implementation of
educational programmes (leaflets, posters, rescue
campaigns, radio and TV spots) have been
developed since 1995 with funding from the
European Union. Management plans for 7 Special
Protection Areas in the islands of Santa Maria,
Terceira, Faial, São Jorge, Graciosa, Flores and
Corvo were produced.
CONSERVATION-ORIENTAT E D
RESEARCH PRIORITIES
The best available knowledge regarding Puffinus
puffinus and Puffinus assimilis populations of the
Azores has allowed us to determine single
management actions and to assist decision making.
However conservation-orientated research is still
lacking:
- Listening for nocturnal vocalisations has been
shown to be the most practical method to
determine the distribution and population levels
of these populations but further research into
vocal activity is needed in order to reduce the
bias of the estimates obtained in this way;
- Extensive surveys to identify new breeding sites
-
-
-
are necessary along the entire coastline of the
archipelago according to the unsurveyed sectors
referred by Monteiro et al. (1999);
Monitoring the breeding sites already identified
is vital to follow population levels and
determine the conservation status. Studies
focusing on the relationships between cliff
characteristics and presence of Puffinus species
are also needed;
Estimation of the impact of predators on local
populations, especially cats and rats, is
fundamental to implement further eradication
programmes;
Comprehensive studies of natural, social and
economic factors and human activities
regarding each SPA of the region is essential to
implement management plans.
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